Our invention relates to a biotransformation process for the production of certain lactones, specifically gamma-decalactone and gamma-dodecalactone or mixtures thereof from the corresponding C.sub.10 and/or C.sub.12 alkanoic acids or hydrolyzates of vegetable oils containing said C.sub.10 and/or C.sub.12 alkanoic acids. Since the natural sources of these lactones are very limited and the use thereof are not economical because usually small quantities exist in fruits and flowers, microbiologists have been seeking alternative ways to increase the product yield and availability of C.sub.10 and C.sub.12 gamma-lactones by means of exploiting various microorganisms.
Thus, considerable time and effort have been expended by microbiologists in the search for better processes for the production of lactones, per se, U.S. Pat. No. 3,076,750 discloses a method of preparing certain optically active lactones and the corresponding hydroxycarboxylic acids by microbial reduction of ketocarboxylic acids. The metabolism of ricinoleic acid by some Candida strains was investigated by Okui, et al (J.Biochemistry, 54, 536-540, 1963) who showed that gamma-hydroxydecanoic acid was an intermediate in the oxidative degradation of ricinoleic acid. However, only trace amounts of gamma-hydroxydecanoic acid were recovered from the fermentation medium due to the metabolysis of gamma-hydroxydecanoic acid upon completion of the fermentation, and the toxicity of ricinoleic acid to the microorganism, which limits the amount of substrate that can be used.
U.S. Pat. No. 4,560,656 provided a method of producing optically active gamma-hydroxydecanoic acid comprising culturing or incubating a microorganism capable of hydrolyzing castor oil, and effecting beta-oxidation of the resulting hydrolysate in the presence of castor oil, to produce gamma-hydroxydecanoic acid.
U.S. Pat. No. 4,560,656 also provided a method of producing optically active gamma-hydroxydecanoic acid comprising enzymatically hydrolyzing castor oil using lipase to form an enzymatic hydrolysate and culturing or incubating a microorganism capable of effecting beta-oxidation of the enzymatic hydrolysate in the presence of said hydrolysate to produce gamma-hydroxydecanoic acid.
U.S. Pat. No. 4,560,656 also provided a method of producing optically active gamma-hydroxydecanoic acid comprising culturing or incubating a microorganism capable of hydrolyzing castor oil and a microorganism capable of effecting beta-oxidation of castor oil hydrolysate in the presence of castor oil to produce gamma-hydroxydecanoic acid.
European Published Patent Application 258,993, published on Apr. 9, 1988, discloses a process for the production of optically active gamma-hydroxydecanoic acid suitable for conversion to optically active gamma-decalactone. The process covers the steps of:
(a) culturing sporobolomyces odorous; and/or rhodotorula glutinis on a medium containing a ricinoleic acid source at 15.degree.-35.degree. C. at a pH of 3-9; and PA1 (b) lactonizing the resulting gamma-hydroxydecanoic acid to gamma-decalactone. PA1 (i) miscibility with decanoic acid and dodecanoic acid; since the solubilities of decanoic acid and dodecanoic acid in water are much less than in oil, mineral oil can be used as an acid reservoir or buffer to prevent an accidental increase in the acid level or decrease in pH; PA1 (ii) high solubility for the lactones; since the lactone product can be continuously stripped out from the aqueous medium and retained in the oil phase, a low level of the lactone can be maintained in the aqueous medium for a prolonged period of time which reduces end product inhibition and toxicity; and PA1 (iii) requirement of a relatively simple downstream process and possibility of recycling of oil; since the lactone and its corresponding acid are major components of the reaction product, comprising about 80-95% of total volatiles retained in the mineral oil, the present invention provides not only a much simpler downstream process, but also provides for the recycling of mineral oil after recovery of the lactone and the acid. PA1 (i) SUPERLA.RTM. white mineral oil #5 NF of Amoco Oil Company; PA1 (ii) SUPERLA.RTM. mineral oil #6 NF of Amoco Oil Company; PA1 (iii) SUPERLA.RTM. white mineral oil #7 NF of Amoco Oil Company; PA1 (iv) SUPERLA.RTM. mineral oil #35 NF of Amoco Oil Company; PA1 (v) BRITOL.RTM. 6 of the Witco Corporation; PA1 (vi) BRITOL.RTM. 9 of the Witco Corporation; PA1 (vii) Carnation White Mineral Oil of the Witco Corporation; PA1 (viii) DRAKEOL.RTM. 6 of the Penreco Corporation; and PA1 (ix) DRAKEOL.RTM. 9 of the Penreco Corporation.
U.S. Pat. No. 5,274,128 (Farbood, et al, I) describes a process for the production of gamma-octalactone which exploits the ability of selected strains from the genera Mortierella, Syncephalastrum and Choanephora to transform caprylic acid or the ethyl ester of caprylic acid to octalactone according to the reactions: ##STR1##
The feeding of the octanoic acid substrate to produce gamma-octalactone using the process of the instant disclosure gives rise to a very low product yield mainly due to an insensitive dissolved oxygen response as the substrate is fed, indicating that the present invention is specific for gamma-decalactone and gamma-dodecalactone production from the respective C.sub.10 and C.sub.12 alkanoic acids.
U.S. Pat. No. 4,960,597 (Farbood, et al, II) issued on Oct. 2, 1990 describes fermentative production of both saturated and unsaturated lactones including the saturated gamma-decalactone from castor oil or ricinoleic acid using a microorganism such as Candida petrophilum, Candida oleophila, Candida sp. and Candida sake according to the reactions: ##STR2## wherein Y represents an oxo-saturated, oxo-unsaturated or diunsaturated C.sub.9, C.sub.11 or C.sub.13 moiety and wherein the number of carbon atoms in X and R are the number of carbon atoms in the Y moiety minus 1.
European Published Patent Application No. 578,338 filed on Jun. 14, 1993 (Farbood, et al, III) describes the fermentation process for preparing 10-hydroxy-C.sub.18 -carboxylic acid and gamma-dodecalactone according to the reaction sequence: ##STR3##
Furthermore, Campanelli and Cooper, THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Volume 67, October 1989, pages 851-855 (Title: "Interfacial Viscosity and the Stability of Emulsions") discloses a study of a mineral oil-water-emulsifier system and discloses the effect on interfacial viscosity of the bioemulsifier produced by the yeast Torulopsis petrophilum.
Although the prior art describes the production of lactones from various substrate sources, nothing in the prior art discloses any biotransformation process that produces high concentrations or high yields of gamma-decalactone and gamma-dodecalactone from the corresponding C.sub.10 and C.sub.12 alkanoic acids wherein the feed rates are controlled by the response of dissolved oxygen tension in the presence of mineral oil as set forth in the instant disclosure.